One chain offered 15 cents off every gallon, but only for one day, a move that made some question the motive behind the promotion.

There are 36 Thorntons gas stations combined in southern Indiana and in Louisville, and they all saw customers take advantage of the sale.

While customers appreciate the break, they were still very skeptical, that it could mean a gas price hike is right around the corner.

"I looked up at the sign and I noticed you save 15 cents using a debit card, so I couldn't pass up on that," said driver Sean Payne.

The news spread fast on large billboards and text alerts.

"Well, it's excellent. Anytime you can save money in this economy and the way gas prices are, you need all the breaks you can get," said driver David Young.

The extra change in customers' pockets Friday created more questions about the change in gas prices in general.

"They always seem to get more expensive on the weekend, which is always when I run out of gas," said driver Kate Denny.

Across the nation, gas prices are in flux. On average, out west, gas is about $4, in middle America, about $3.50 and the Louisville region, about $3.30 and in the lower southern states, most areas are right around $3.

"You have to remember, crude oil is a component of gasoline, but gasoline is a commodity within itself," said John Zikias, senior vice president of Supply and Category Management for Thorntons.

Zikias said while crude oil prices may be low or high, gasoline is it's own commodity with it's own impact, which affects pricing across the nation.

"There's been a number of refineries that have closed on the east coast this year. Several in New Jersey, one in Puerto Rico," said Zikias.

That puts a squeeze on the market. Throw in the maintenance of refineries, plus differing city taxes where gas stations are located, various traders on the market and gas prices fluctuate with or without crude oil prices.

Another reason is competition between neighboring stations and the differing formulations of the gas they sell.

"So for instance, you get to Bullitt County, they're not using reformulated gasoline and that's a less expensive gas, so you could see a 15-cent difference as you get out of Jefferson County," said Zikias.

While customers were skeptical, they said they would take a break when they can get it.

"When you can save an additional 15 cents, it makes a big difference," said Young.

The 15-cent deal ended at midnight, but the up-and-down roller coaster of gas prices won't. Analysts said that's here to stay.

To give an idea of how gas and crude oil prices have changed over the years; according to the New York Stock Exchange, in 2006 crude averaged about $65 per gallon and gas was just more than $3.

Three years later, crude was up to $69 while the price for gas had dropped 44 cents.

And in 2011, crude was nearing $100 as gas prices hovered around $3.60 per gallon.